MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, ENABLED_TOOLS and TOOLSETS are applied when tools are listed but are not rechecked when a tools/call request is dispatched. A client that knows a hidden tool name can directly invoke excluded read, write, or delete tools despite the operator's configured least-privilege restrictions. The advisory traces the vulnerable input and processing flow through ENABLED_TOOLS, TOOLSETS, tools/list, tools/call, and _call_tool_mcp, which identify the affected entry points, controls, and code paths. This issue is fixed in version 0.22.0.
CVE-2026-77243
HIGHPre-NVD 8.88.8—Trending — 3 sources updated this weekElevated
EchelonGraph scoreMEDIUM confidence
This high-severity CVE scores 8.8 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 57% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: epss, secondary
8.8EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
- High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 1%CVSS: 8.8Exploit: Elevated riskExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 8.8
- EG Score
- 8.8(medium)
- EG Risk
- 56(Track*)EG Risk 56/100SSVC: Track*
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity88% × 45%Exploitation40% × 40%Automatability0% × 15%Action: Watch closely — could escalate to Attend. - EPSS PROB
- 1%
- EPSS %ILE
- 43%
- KEV
- Not listed
Published
September 22, 2026
Last Modified
September 23, 2026
Advisory Details (4)
Auto-updated Sep 22, 2026🔬 Proof of concept available. Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available
v0.22.0
Patch available: sooperset/mcp-atlassian v0.22.0
https://github.com/sooperset/mcp-atlassian/releases/tag/v0.22.0github_commit Patch Available
commit b041733473f9 (sooperset/mcp-atlassian)
Patch available: sooperset/mcp-atlassian v0.22.0 (contains commit b041733473f9)
https://github.com/sooperset/mcp-atlassian/commit/b041733473f95119dd539542a43c280737a8e460github_pr Patch Available
Security hardening across attachment, transport, SSRF, authorization, filter, and OAuth layers
Patch available: sooperset/mcp-atlassian v0.22.0 (PR #1448 merged 2026-07-10)
https://github.com/sooperset/mcp-atlassian/pull/1448github Patch Available🟡 PoC Available
ENABLED_TOOLS / Toolset authorization bypass in mcp-atlassian · Advisory · sooperset/mcp-atlassian · GitHub
https://github.com/sooperset/mcp-atlassian/security/advisories/GHSA-3r68-hf9h-887vVendor Advisories for CVE-2026-77243(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Affected Packages
(1 across 1 ecosystem)
PyPI(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| mcp-atlassian | 0.1.1 ... 0.9.0 (79 versions) | 0.22.0 | — |
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 7× in last 7d / 7× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-09-23 18:37 UTCEG score recompute
- 2026-09-23 17:54 UTCEPSS rescore
- 2026-09-22 19:37 UTCEG score recompute
- 2026-09-22 19:08 UTCEG score recompute
- 2026-09-22 18:30 UTCEG score recompute
- 2026-09-22 18:08 UTCEG score recompute
- 2026-09-22 18:08 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(5)
What is CVE-2026-77243?
CVE-2026-77243 is a high vulnerability published on September 22, 2026. MCP Atlassian is a Model Context Protocol (MCP) server for Atlassian products (Confluence and Jira). Prior to 0.22.0, ENABLEDTOOLS and TOOLSETS are applied when tools are listed but are not rechecked when a tools/call request is dispatched. A client that knows a hidden tool name can directly invoke…
When was CVE-2026-77243 disclosed?
CVE-2026-77243 was first published in the National Vulnerability Database on September 22, 2026, with the most recent update on September 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-77243 actively exploited?
CVE-2026-77243 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 1% probability of exploitation in the next 30 days, which ranks it in the top 56.6% of all scored CVEs.
What is the CVSS score of CVE-2026-77243?
CVE-2026-77243 has a CVSS v3 base score of 8.8 (NVD).
How do I remediate CVE-2026-77243?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77243, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-77243
Is Your Infrastructure Affected by CVE-2026-77243?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.